1. Field of the Disclosure
The present disclosure relates generally to the field of production of semiconductor components and integrated circuits, and, more particularly, to rapid heating processes, such as laser heating processes, and controlling them in the framework of the production of semiconductor components.
2. Description of the Related Art
In modern integrated circuits, a very large number of individual circuit elements, such as field effect transistors in the form of CMOS, NMOS, PMOS elements, resistors, capacitors and the like, are produced on a single chip surface. The structure dimensions of these circuit elements are typically continuously reduced following the introduction of every new circuit generation to provide currently available integrated circuits with improved performance in terms of speed and/or power consumption. Reducing the size of the transistors is an important aspect for the continued improvement of component performance in complex integrated circuits, such as CPUs. The reduction in size is typically associated with an increase in switching speed, thereby improving signal processing performance.
In addition to the large number of transistor elements, a plurality of passive circuit elements, such as capacitors and resistors, are typically also provided in an integrated circuit, as required by the basic circuitry structure. Due to the smaller dimensions of the circuit elements, not only the performance characteristics of the individual transistor elements are improved, but also their packing density is increased, as a result of which it is possible to incorporate more and more functions into a given chip surface. For this reason, very complex circuits have been developed, which may comprise different types of circuits, such as analog circuits, digital circuits and the like, thereby providing complete systems on a single chip (SoC).
Transistor elements can, in complex integrated circuits, be regarded as essential circuit elements, which determine the overall performance of the semiconductor components. In the course of continuous improvement of the performance of transistor elements, differently doped regions are formed in the semiconductor substrate, on and in which the transistor elements are formed. Activation of the dopants is generally affected by way of rapid heating processes (rapid thermal anneal), for example by way of lasers (laser anneal). For example, ultra-shallow junctions are provided in high-performance transistors of a certain class that contact the source/drain regions and extend partly below the gate electrode in the semiconductor substrate. Activation of the dopants in these junctions and of dopants in deep source/drain regions and halo regions can be affected by way of a very rapid and local laser heating process, so-called laser spike annealing (LSA), in which irradiation takes place over a period of a few milliseconds or less. However, the problem of accurately aligning such rapid local laser heating processes, such as LSA, arises, i.e., precisely positioning the laser exposure surface on the wafer to be processed. Only accurate alignment of the wafer with the laser beam and controlling the geometric shape and centering of a region on the wafer surface heated by laser annealing allows for reliable heating at, and only at, the desired position. In addition, the laser beam must be prevented from striking an edge of the wafer, since this can cause the wafer to fracture. On the other hand, there is a growing need to utilize the wafer as completely as possible, i.e., to minimize the edge waste.
Inspection of the heated regions and, in particular, the transition regions of heated and non-heated regions on the wafer is conventionally performed by visual inspection of the wafer after it has been exposed to the heating process or with the aid of measuring its electrical resistance using, for example, 4-point probes. It is, therefore, made use of the fact that the electrical resistance strictly correlates with the heating temperature of the region on the wafer exposed to the heating. The visual inspection is disadvantageous because of the time required and the inherent inaccuracy or the subjective moment, respectively. The resistance measurement method is disadvantageous in that it is time-consuming and allows only for a limited resolution.
In view of the situation described above, the present disclosure relates to techniques of semiconductor manufacture using rapid heating processes, such as (rapid) laser heating and flash lamp heating, and to controlling such heating processes in the context of semiconductor manufacture.